RU2460204C1 - Autonomous starter-generator power supply system - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: system comprises one inverter and one electric machine, operating as a start or as a generator, during the start the inverter provides for development of a rotating electromagnetic field and rotation of a rotor in accordance with any available program, and in the generation mode the inverter operates as a rectifier and a step-up controller of DC voltage. Its transition into the generation mode is realised with a switch of control units power supply by a signal of an electric machine rotor rpm controller, afterwards in turns, by half-cycles, power keys of the inverter are controlled from a metering element of output voltage via two width-pulse modulators.

EFFECT: stabilisation of voltage on loads with reduction of their weight and cost of a system.

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Description

The invention relates to the field of electrical engineering, providing power to autonomous objects. Such objects include, for example, aircraft, vehicles. In many of the aforementioned facilities, the loads are supplied with a constant voltage of 27 V, while it is necessary to ensure both autonomous starting of the engine of the facility, and providing the loads with stabilized constant voltage with the most stringent requirements for the mass and dimensions of the system.

Known [1] starter-generator electric power plant, providing power to the loads and starting the internal combustion engine. In this installation, one electric machine and one converter with a DC link and an inverter are used to start and generate, which ensures a reduction in mass and cost. However, this installation provides loads with alternating current and cannot be applied in DC systems.

Known [2] is a method of controlling a valve actuator and an electric actuator [3], which provides a braking mode due to alternating pulse-width control of all power switches of a three-phase inverter connected to a positive bus, and then the keys connected to a negative power bus.

In the proposed starter-generator power supply system, the control method for braking the electric drive is used in the generating mode, and the proposed circuit is equipped with additional control units to minimize the weight and cost of the system while stabilizing the voltage. The technical result is achieved due to the fact that the autonomous starter-generator system of direct current power supply, equipped with a starting source of electricity, for example, a battery, contains an internal combustion engine, mechanically connected to an electric machine, which at start-up works as an engine, and in operating mode, as a generator moreover, the stator windings of the electric machine are connected to a three-phase bridge inverter on semiconductor switches connected through matching cascades to the control system by starting and with a two-channel system of pulse-width modulators, the output of the first channel through the matching stages connected to the semiconductor switches connected to the positive bus of the power supply system, and the output of the second channel connected to the keys connected to the negative bus, each channel has two inputs, the first inputs are connected to the antiphase outputs of the sawtooth generator, and the loads of the power supply system are connected to the DC buses through a contactor and a buffer battery an inverter, and a voltage measuring organ is connected to the load power terminals, the output of which through an amplifier is connected to the second inputs of each channel of a pulse-width modulator, the system being equipped with a rotor speed controller of an electric machine, which is connected via a threshold element to the power switch of the control units for starting and generating with regulation of the output voltage of the DC power supply system.

The system is presented in figure 1, where it is indicated:

1 - Electric machine with a permanent magnet rotor;

2 - Three-phase inverter on semiconductor switches, shunted by diodes;

3 - The main engine of the object, such as a turbine;

4 - Storage capacitor on the DC bus of the inverter;

5 - rechargeable battery;

6 - Starting contactor;

7 - Power grid autonomous object;

8 - Matching cascades, for example drivers;

9 - launch control system;

10 - Speed controller with a threshold element;

11 - Power switch control units;

12 - sawtooth voltage generator;

13 - Measuring body of the output voltage with an amplifier;

fourteen; 15 - The first and second pulse width modulators.

The proposed system works as follows.

When starting, contacts 6 of the starting device are closed. From the battery 5, power is supplied to the loads 7 and to the ignition system of the internal combustion engine 3. At the same time, through the contacts of the switch 11, power is supplied to the block 9, which provides the start control program, and through the cascading stages 8, the power semiconductor switches of the inverter 2 begin to be switched, so that in the stator electric machine 1, a rotating electromagnetic field is formed. As a result, the rotor of the electric machine 1, mechanically connected with the internal combustion engine 3, begins to rotate, and upon reaching a certain speed, a steady start of the engine 3 is carried out with a subsequent increase in speed.

The controller 10 of the revolutions with a threshold element monitors the number of revolutions and, with a given value, provides the switch 11 to switch the power supply from block 9 to blocks 14 and 15. The signals from the sawtooth generator 12 are sent to the same blocks. Moreover, positive signals are sent to one block half wave of sawtooth voltage, and negative half wave of sawtooth voltage is applied to another block. A signal is supplied to the same blocks from the measuring organ 13, which is compared with the corresponding sawtooth voltage. If the output voltage is equal to the specified one, then the signal from the measuring body 13 exceeds the signal from the sawtooth voltage generator 12. In this case, all the semiconductor switches of the inverter 2 are closed and it works as a three-phase bridge rectifier, supplying electricity to the load 7 and recharging the battery 5.

When the output voltage decreases, the signal from the measuring body 13 decreases and for a certain time t the sawtooth voltage signal exceeds it. In this case, all the power switches of the inverter 2 connected to the positive or negative bus, depending on which of the modulators the signal goes, open (see the diagram of figure 1).

As a result, at the sawtooth half-wave period T / 2, for the time t, the three semi-drive switches connected to the same bus are open, and closed (T / 2-t).

Energy for time t is stored in the shorted stator windings and in the external inductors indicated by a dotted line in figure 1, and at stage (T / 2-t) it is discharged into the capacitor 4. The output voltage will increase. If the semiconductor switches of inverter 2 have built-in current protection, then external inductors are not required. For a steady process, in continuous current mode, the output voltage will be determined by the expression

As a result, due to the feedback action, the output voltage will stabilize.

достигнет значения 0,5.If the speed of the main engine 3 decreases by half, the voltage across the windings of the electric machine 1 decreases by half, and the ratio

reaches a value of 0.5.

In this case, the output voltage at the loads decreases only by the value of the static error of the control system.

As a result, the proposed starter-generator system will supply the loads of an autonomous object with a stabilized constant voltage at the simplest power unit, and therefore, with a minimum weight and cost.

Information sources

1. Patent for invention No. 2363090 dated January 21, 2008

authors Laptev NN, Kharitonov S.A.

2. Patent for invention No. 2398348 dated 01.12.2008.

author Laptev N.N.

3. Patent for utility model No. 82077 dated December 5, 2008.

authors Laptev N.N., Levin A.V., Dovgalenok V.M., Khodunov M.F.

Claims (1)

Autonomous starter-generator DC power supply system, equipped with a starting source of electricity, for example a battery, containing an internal combustion engine, mechanically connected to an electric machine, which at start-up works as an engine, and in operating mode - as a generator, and the stator windings of the electric machine are connected to a three-phase bridge inverter on semiconductor switches connected through matching cascades to a start-up control system and to a two-channel latitude system -pulse modulators, and the output of the first channel through matching cascades is connected to semiconductor switches connected to the positive bus of the power supply system, and the output of the second channel is connected to switches connected to the negative bus, and each channel has two inputs, the first inputs of which are connected to antiphase outputs sawtooth voltage generator, characterized in that the loads of the power supply system through the contactor and the buffer battery are connected to the DC buses of the inverter, and to the power terminals the load is connected to a voltage measuring organ, the output of which through the amplifier is connected to the second inputs of each channel of the pulse-width modulator, and the system is equipped with a rotor speed controller of the electric machine, which is connected via a threshold element to the power switch of the control units for starting and generating modes with regulation of the output voltage DC power supply systems.